Solution to A researcher is interested in the effects of exercise on mental health and he proposes … - Sikademy

Feb. 25, 2021

Archangel Macsika Sikademy Image

Archangel Macsika

A researcher is interested in the effects of exercise on mental health and he proposes the following study: Use stratified random sampling to ensure representative proportions of 18-30, 31-40 and 41- 55 year olds from the population. Next, randomly assign half the subjects from each age group to exercise twice a week, and instruct the rest not to exercise. Conduct a mental health exam at the beginning and at the end of the study, and compare the results.


a) What type of study is this?


b) What are the treatment and control groups in this study?

The treatment group is the group that exercises 2 times a week.

The control group is the one that does not exercise.

c) Does this study make use of blocking? If so, what is the blocking variable?


The blocking variable is age.

The blocks are 18-30 year olds, 31-40 year olds 41-55 year olds.

d) Does this study make use of blinding?


The patients know if they are in the group that exercises or the one that doesn’t.

e) Comment on whether or not the results of the study can be used to establish a causal relationship between exercise and mental health, and indicate whether or not the conclusions can be generalized to the population at large.

One can establish a causal relationship and one can generalize to the population at large (because it came from random sampling).

One possible issue is how much the patients used to exercise before the experiment.

Maybe some active people were sent to the no-exercise group and vice versa.

f) Suppose you are given the task of determining if this proposed study should get funding. Would you have any reservations about the study proposal?

As mentioned above, one reservation I would have is that it’s unclear if the effect would come from having people outside their comfort zone or from the actual exercising.

It’s also a little morally dubious to force people not to exercise.

A better idea would be to have an experiment where you split into one group that exercises once a week more than before and a control group that exercises the same as before.